The invention relates to a device according to the preamble of patent claim 1.
Such a device is known from U.S. Pat. No. 4,341,568.
Moreover, disposable pipette tips are known from the prior art. Such disposable pipette tips are marketed, for example, by the Eppendorf company.
They are used in many analysis processes for separating bonded and solid phases in a reaction vessel with a subsequent washing process for the solid phase. One example is the immunoassay, in which the solid phase may be present in the form of magnetic particles or in the form of so-called xe2x80x9ccoated tubesxe2x80x9d. In the case of xe2x80x9ccoated tubesxe2x80x9d, the solid phase is at the same time the wall of the reaction vessel. The washing process in each case comprises three steps:
a) sucking out the reaction solution which is to be discarded, the solid phase being retained,
b) adding washing solution,
c) sucking out the washing solution, and, if appropriate,
d) repeating the steps described under letter b and letter c.
Particularly when isolating and purifying nucleic acids with a subsequent amplification reaction, it is necessary for there to be no contamination to the analysis sample during the washing step. The polymerase chain reaction is particularly sensitive to contamination. Such contamination may be caused by aerosols formed when washing solution is being introduced and sucked out and which propagate through the air, resulting in carry-overs from one reaction vessel to the next.
The object of the invention is to eliminate the drawbacks of the prior art. The intention in particular is to provide a device which can be used to carry out contamination-free delivery and discharge of liquids into and from a reaction vessel and with which it is possible to suck out in a controlled manner a liquid supernatant which lies above solid particles which have been deposited at the bottom of the reaction vessel.
This object is achieved by means of the features of patent claim 1. Expedient configurations of the invention result from the features of claims 2 to 16.
According to the invention, the tube is designed so as to taper conically toward the first opening. As a result, it is possible to suck out a liquid supernatant in a controlled manner. When washing solution is being sucked out through the tube, there is no possibility of, for example, nucleic acids which are bonded to magnetic particles being sucked in.
Advantageously, the first connection fitting is situated inside the second connection fitting. This allows a particularly space-saving design of the device.
According to a further feature, the second connection fitting may have a flange. This is used to limit the insertion depth when the device is inserted into a reaction vessel.
Expediently, the second connection fitting is in communication with an annular passage which surrounds the tube, the annular passage parallel to the inner wall of the reactive vessel, thus effecting a seal. A conical section, which is connected to the outer wall of the tube, may adjoin the cylindrical section. In this case, the second opening is advantageously situated in the conical section. The cylindrical section is advantageously designed in such a way that it can be inserted into the reaction vessel.
According to a further feature, the device may be made from conductive plastic. As a result, it is possible to derive a signal which represents the filling level in the reaction vessel and as a result to control the filling level automatically.
According to a particularly advantageous feature, 96 reaction vessels are combined together as a xe2x80x9c96-well titration platexe2x80x9d. As a result, it is possible to wash 96 different samples at the same time.